The record of mid Cretaceous oceanic anoxic events from the Ionian zone of southern Albania

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• 作者：Taniel Danelian ; Franç ; ois Baudin ; Silvia Gardin ; Edwige Masure ; Caroline Ricordel ; Ilia Fili ; Teuta Meç ; aj ; Kristaq Muska
• 关键词：Albania ; Ionian zone ; Dinoflagellates ; Calcareous nannofossils ; Radiolaria ; Organic geochemistry ; Oceanic anoxic events
  Mots clé ; s ; Albanie ; Zone ionienne ; Dinoflagellé ; s ; Nannofossiles calcaires ; Radiolaires ; Gé ; ochimie or
• 刊名：Revue de Micropaleontologie
• 出版年：2007
• 出版时间：July-September 2007
• 年：2007
• 卷：50
• 期：3
• 页码：225-237
• 全文大小：2242 K

文摘

Along the Sopoti section of Mali Gjere mountain are found two distinct mid-Cretaceous marly-shaly-siliceous intervals that occur near the top of the Vigla Limestone Formation (Aptian–Albian) of the Ionian zone in southern Albania. The lower interval is relatively rich in carbonate content (36 % CaCO₃ on average) and radiolaria (10 % on average). It contains black shale levels rich in organic matter (up to 8.5 % total organic carbon (TOC)) of marine origin, which did not experience any strong thermal maturation as suggested by their very low T_max values. The age of the lower interval is latest Barremian to Early Aptian based on its calcareous nannofossil and radiolarian assemblages. It is therefore regarded as the equivalent of the Fourcade Level of Greece, reflecting the Oceanic Anoxic Event 1a (OAE1a). The upper interval is richer in both carbonate content (60 % CaCO₃ on average) and radiolaria (20 % on average) but it is practically devoid of any preserved organic matter. Its age straddles the Aptian–Albian boundary based on integrated biochronologic data of dinoflagellates, calcareous nannofossils and radiolaria. It is tentatively considered as the sedimentary expression of OAE1b (sensu Leckie et al., 2002) in the Ionian zone of Albania. The presence of large Assipetra nannoliths in both shaly-siliceous intervals and the relative abundance of radiolaria suggest that their accumulation took place during periods of higher productivity in the Ionian zone of Albania.